Skin preparation device and biopotential sensor

ABSTRACT

The skin preparation device and sensor of the present invention include an array of rigid tines. The tines serve to “self-prepare” the skin at each electrode site. These tines, when pressed against the skin, penetrate the stratum corneum, thereby reducing skin impedance and improving signal quality. A self-prepping device of the present invention is an optimized array of short non-conductive rigid tines in which the individual tines are created in a geometry that allows for a sharp point at the tip when molding, machining or etching is used as a method of fabrication. This non-conductive array with rigid penetrating structures may, therefore, be used in combination with a conductive medium, preferably an ionic conductive gel. In penetrating the stratum corneum, micro-conduits are created in the layers of the skin enabling the conductive medium to reach the low impedance layers and to transmit bioelectrical signals from the skin to the electrode surface. Such a self-prepping device can be readily mass produced using molding methods or possibly other manufacturing methods, thereby providing for a low cost means of achieving improved performance of the biopotential sensor. Additionally this invention includes the integration of this self-prepping device into a biopotential sensor comprising an array of one or more electrodes.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of Provisional Application Ser. No.61/126,849, filed on May 2, 2008.

BACKGROUND OF THE INVENTION

This invention relates to a skin preparation device that can be used topenetrate the outermost layer of skin to allow for the penetrationand/or displacement of the stratum corneum. A typical use of suchinvention is in the noninvasive monitoring of electrophysiologicalsignals. This skin preparation device may be integrated into theelectrodes of a biopotential sensor.

The human skin tissue is composed primarily of connective tissue, thedermis, covered by a protective layer, the epidermis. The outermostlayer of the epidermis is the stratum corneum. In the study ofelectrophysiological monitoring using surface electrodes, the stratumcorneum is significant, due to its function as a protective barrier. Thestratum corneum is on average approximately 20 μm thick, and is composedprimarily of denucleated, dead skin cells that are inherently a sourceof high electrical impedance. Very low amplitude signals are associatedwith some electrophysiological recordings, particularlyelectroencephalography (EEG); therefore, it is important to optimize thesignal acquisition and minimize noise artifact. Thus, impedance measuredat the interface between a patient's skin and the electrode used foracquiring the electrophysiological signals is an important considerationin biopotential monitoring. Additionally, variance in impedance betweenelectrode sites can result in unwanted noise in the signal. Goodelectrical conduction between the patient's skin and the electrode canbe better achieved by removing or penetrating the stratum corneum layerof the epidermis.

The most common electrodes that are applied to the surface of the skinoften require that the skin be prepared before the electrode is applied.Preparation of the skin typically begins with cleaning off the surfacewith alcohol to remove dirt and oils, followed by abrasion of the skin'ssurface with an abrasive material or a grit-impregnated gel to removethe stratum corneum layer. To simplify the skin preparation process thatis required prior to application of an electrode, several forms ofself-prepping electrodes have been developed. Such electrodes, whichhave an integrated mechanism for achieving this preparation of the skin,provide numerous advantages over standard EEG or electrocardiogram (ECG)electrodes because they eliminate the need for the additional step ofskin preparation as well as the need to have the abrasive materialavailable in a clinical setting.

In many of these developments, the means by which the skin preparationoccurs is by employing a textured component in contraction with theelectrode, which when pushed against the skin attempts to abrade orpenetrate the outermost layer. This textured component may be a part ofthe electrode surface itself or an independent part affixed to theelectrode surface. International Patent Application WO 02/00096A2describes a means of collecting EEG using a “volcano tip” tinestructure, in which tines formed from perforations in the electrodematerial are used to abrade the outer layers of skin and improveelectrical contact. This application does not describe the design ormanufacturing procedures for the volcano tip tine structure.

U.S. Pat. No. 5,305,746 issued to Fendrock et al. describes an electrodewhich provides a textured component by way of an integrated array ofnon-conductive flexile tines. The flexile tines are of length0.025″-0.110″ and of thickness 0.002″-0.015″, and are embedded in a wetconductive gel. The flexile tines part the stratum corneum layer toexpose the low impedance layers without scratching or abrading deeperlayers of the skin. Although this device does generally reduce themeasured impedance at the skin to electrode (skin to gel) interface, themechanism by which flexile tines part the skin varies from person toperson and skin type to skin type. Long flexile tines lack uniformity oforientation and insertion angle into the skin. Rigid tines may providebettor control over the tine orientation and the mechanism by which theybypass the stratum corneum. Due to their size, macro-sized tines, asdescribed in U.S. Pat. No. 5,305,746, limit the potential density of thetines in the array thereby also limiting the ability to reduce theoverall electrode size and overall area of skin that is affected whilemaintaining equivalent signal quality. In addition, long tinesfacilitate being pressed too deeply into the skin causing unnecessarypenetration beyond the stratum corneum while a shorter tine limits thedeformation of the skin. Consequently, the advantage of an array ofshorter and more rigid tines is that they can produce more repeatablelow impedance signals with potentially less irritation of the skin.

U.S. Pat. No. 5,309,909 issued to Gadsby discloses a skin preparationand monitoring electrode that penetrates a patient's skin prior toacquiring biopotentials. The electrode has tines, mounted on the concavesurface of a dome, that penetrate first the conductive layer of theelectrode and then the skin when force is applied to the dome causing itto deflect towards the skin. Upon cessation of the application of force,the tines retract with the movement of the dome. The complexity of thisdesign does not support the cost effectiveness and ease of manufacturingrequired for a disposable electrode and skin preparation device.

The concept of using an array of shorter rigid tine structures for skinpenetration is commonly associated with the applications of biopotentialsignal acquisition and transdermal drug delivery mechanisms. Among rigidtine array designs presented in journal and patent literature, there isa variety of tine array structures, materials, and dimensions, alloptimized for their particular application.

International Patent Applications WO 2004009172A1, WO 2007075614A1, WO2007081430A2 describe microneedle devices for delivering a drug to apatient via the skin. These needles typically have a channel through themiddle allowing fluid to pass through the microneedle array or they arecoated with a drug, or active component that is intended to dissolve inthe skin beneath the stratum corneum. These needles for transdermal drugdelivery have no conductive requirement because they do not serve totransmit any electrical signal away from the skin. These microneedlesutilize lithographic processes on silicon in order to be created at suchsmall scale.

An example of an additional application of an array of spikes used toachieve electrical contact with a series of very closely locatedelectrode sites is described in U.S. Pat. No. 7,103,398 B2, issued toSieburg. In this patent Sieburg describes a device for sensingelectrical signals on the surface of human or animal skin. The device iscomprised of a substrate containing a plurality of electrodes with eachof those electrodes having one pointed contact end facing away from thesubstrate. In this design, each pointed contact, or “tine” is coupledelectrically to an independent electrode site, rather than havingmultiple tines together penetrate an area of skin from which the signalwill be conducted to the electrode surface.

U.S. Pat. No. 6,622,035, issued to Merilainen et al. also aims toeffectively acquire biopotential signals with an electrode comprising anarray of cylindrical or tapered “spikes” to make the skin morepermeable. Each electrode is described as having 100-10,000 (ideally400-2000) spikes per electrode, with the length of the spikes rangingfrom 50-250 μm (≦010″) from the carrier or electrode surface. Asubsequent patent, U.S. Pat. No. 6,961,603, also issued to Merilainendescribes the same spike geometry and spike density; however such patentalso teaches injection molding the “spikes” using a non-conductivematerial which will then be coated with a conductive layer such assilver-silver chloride. Such “spike” arrays, in addition to beingconductive, are very small in size, fine in geometric characteristicsand high in number spikes per array. These factors result in a non-costeffective design for molding, particularly for a disposable device.

U.S. Pat. No. 6,690,959, issued to Thompson also teaches the use of“nano-spikes” to penetrate the epidermis of the skin for collectingelectrical biopotentials. The spikes are formed using aMicroelectromechanical System (MEMs) construction technique and aresubsequently coated with a conductive metal. Besides an indication thatthe nano-spikes are 10 μm in length and have an angularly disposed endshaped to assist in penetration of the cornified layer of the skin, nofurther detail regarding the geometry of the spikes is offered.

Similar biopotential signal acquiring devices have been created usingcarbon nanotubes. This approach is a highly effective means of creatingvery small, conductive tines in an array, however the cost and timeassociated with the growth of these arrays is currently prohibitive forintegration into a high volume disposable product. The same drawbacksapply to microneedles formed using dry-etching of silicon, as it is amulti-step manufacturing process with high development costs.

One object of the proposed invention is the transduction of lowimpedance electrophysiological signals using a device that employs anarray of sharp, rigid structures that can be integrated into a set ofone of more electrodes to conduct the signals to a monitoring system. Afurther object is to provide a device that can be mass produced, forthis application, at a cost appropriate for a disposable use product.

SUMMARY OF INVENTION

The device of the present invention includes an array of rigid tines.The tines serve to “self-prepare” the skin at each electrode site,providing for sufficiently low impedances required to collect highquality electrophysiological signals. These structures, when pressedagainst the skin (i.e., “prepping the skin”), penetrate the stratumcorneum, thereby reducing skin impedance and improving signal quality.The function of this invention is to acquire repeatable bioelectricalsignals with impedance less than 20 kΩ per electrode. Thesebioelectrical signals can then be transmitted from the electrode surfacevia the sensor conductors (leads) to the monitoring system. Aself-prepping device of the present invention is an optimized array ofshort non-conductive rigid tines in which the individual tines arecreated in a geometry that allows for a sharp point at the tip whenmolding, machining or etching is used as a method of fabrication. Thisnon-conductive array with rigid penetrating structures may, therefore,be used in combination with a conductive medium, preferably an ionicconductive gel. In penetrating the stratum corneum, micro-conduits arecreated in the layers of the skin enabling the conductive medium toreach the low impedance layers and to transmit bioelectrical signalsfrom the skin to the electrode surface. Such a self-prepping device canbe readily mass produced using molding methods or possibly othermanufacturing methods, thereby providing for a low cost means ofachieving improved performance of the biopotential sensor. Additionallythis invention includes the integration of this self-prepping deviceinto a biopotential sensor comprising an array of one or moreelectrodes.

The specific invention described herein of tines within a tine array,which can be integrated into the electrodes of a biopotential sensor, isoptimized for performance in a specific application and additionally isoptimized for successful and cost effective manufacturing by injectionmolding methods. An alternative method of manufacturing may includemicromachining and resin casting from a mold. Post processes may includea vacuum depositioning of precious metals or conductive ink layering ifa conductive part is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of an embodiment of the sensorsystem in use.

FIG. 1B is a top plan view of an embodiment of the sensor system

FIG. 1C is an enlarged perspective view of a skin preparation deviceincorporated in a sensor system.

FIG. 2 is a perspective view of one embodiment of a skin preparationdevice.

FIG. 3A is a perspective view of a second embodiment of a skinpreparation device.

FIG. 3B is a top plan view of the second embodiment of the skinpreparation device.

FIG. 3C is a front cross-sectional view of the embodiment of FIG. 3A.

FIG. 3D is a side cross-sectional view of the embodiment of FIG. 3A.

FIG. 4A is a perspective view of a third embodiment of the skinpreparation device.

FIG. 4B is a top plan view of the embodiment of FIG. 4A.

FIG. 4C is a side view of the embodiment of FIG. 4A.

FIG. 5A is an enlarged perspective view of an embodiment of the tines ofa skin preparation device.

FIG. 5B is a side view of the tines shown in FIG. 5A.

FIG. 5C is a front view of the tines shown in FIG. 5A.

FIG. 6 is a perspective view of an embodiment of a skin preparationdevice including a separate gel chamber.

FIG. 7A is a perspective view of an embodiment of a skin preparationdevice.

FIG. 7B is an enlarged perspective view of a tine of the embodimentshown in FIG. 7A.

FIG. 7C is an alternate embodiment of the skin preparation device shownin FIG. 7A.

DETAILED DESCRIPTION OF THE INVENTION

A biopotential sensor 12 shown in FIGS. 1A and 1B is a device thatcontains an array of one or more electrodes 14 and a set of conductorsthat provide an electrical conduction path for the acquired signals fromthe electrodes 14 to a single terminating connector 16 which in turnconnects to the mating receptacle 18 of the biopotential monitoringsystem 20. The sensor device 12 may be coupled to the monitoring systemvia a terminating connector 16 inserted into a mating receptacle 18 onthe monitoring system 20. Once electrical connection is achieved, themonitoring system 20 may perform analysis of the acquired biopotentialsignals.

The biopotential sensor 12 includes one or more electrodes 14. In theembodiment of the biopotential sensor 12 shown in FIG. 1B, the sensor 12is comprised of four electrodes 14. In this embodiment, the sensor 12includes a flexible substrate 22 with an adhesive layer on at leastportions of the substrate 22 to enable secure placement on the skin. Notshown in the figure are the conductors which may be printed on thesubstrate 22 with conductive material or alternately be a set ofconductive wires mounted on the substrate 22, and the terminatingconnector which enables connection of the conductors to the monitoringsystem. The electrodes 14 that comprise the sensor 12 may be formed witha layer of conductive material preferably silver/silver chloride, whichmay be printed. Alternately the electrodes may incorporate asilver/silver chloride coated surface in contact with a post or stud onthe opposite (non-patient contacting) surface. The post or stud makeselectrical contact via a common EEG snap or a pre-attached wire, betweenthe electrode surface and the conductors to the connector. Theconductive surface of the electrode may also be formed of conductivecarbon.

The surface of the electrode 14 may be coated with a conductive medium,preferably an ionic conductive wet gel, comparable to those commerciallyavailable for the application of signal acquisition. Alternately, asolid conductive gel may be used to coat the surface of the electrode14. In another embodiment, the conductive gel may be both a conductivemedium as well as an adhesive. The conductive gel provides continuouscontact between the electrode surface and the surface of the skin evenif the electrode substrate does not conform precisely to the curvatureof the electrode site on the skin. In yet another embodiment theelectrode 14 area may contain a sponge to keep the electrolytic gel insuspension.

Referring to FIG. 1C, included as part of the electrode 14 of thisbiopotential sensor 12 is a prepping device which is an array 26 ofrigid tines 24. In one embodiment, the tine array 26, or multiple tinearrays, may be affixed to the electrode(s) 14 with an adhesive either onthe bottom surface of the tine array 26 base or around its perimeter.The tine array 26 may be positioned such that a portion of the length ofthe tines 24 in a tine array 26 extends above the adhesive layer whichmay be on the flexible sensor substrate 22. In an alternate embodiment,the tine array 26 is not part of an array of electrodes 14, but insteadis a separate component that is utilized to prepare the skin.

The rigid tines 24 may remain in contact with the skin and still remainaffixed to the electrode surface once the electrode 14 with the preppingdevice on the sensor 12 has been pressed firmly against the skin. Thetines 24 may retract from the skin once pressure is no longer beingapplied. In either arrangement pressing the electrode 14 toward the skinallows the tine structure to displace or penetrate the stratum corneumand allows the bioelectrical signal to be conducted from the skin to theelectrode surface by way of the conductive gel in which the tines areembedded. In one embodiment, the conductive gel may be applied to thetop surface of the tine array 26 or alternately it may be contained in asponge which may overlay the tines. A preferred tine height is0.020″-0.040″, however the tine height may range from 0.010″-0.080″,ensuring that the tine will efficiently create micro-conduits throughthe depth of the stratum corneum, while at the same time limiting theamount of deformation of the skin. The decreased height of the tine 24in combination with small tine size minimizes sensation on the skinduring the process of prepping the sensor 12. An adhesive layer, whichcould be adhesive backed foam, on the perimeter of the electrode 14 maybe employed to create a central cavity in which the tine disk issecured. The small size of the tines 24 and the reduced number of timesallow the electrode 14 to be worn comfortably for long periods of time.The application procedure does not require specialized training and thuscan be performed by any person, including self preparation by thesubject of the biopotential recording. Furthermore, it eliminates theneed for initial skin preparation by separate abrasive materials or gelsprior to electrode application.

In some embodiments, the rigid tine array 26 is formed from anon-conductive material. This same nonconductive material is used toform both the base of the tine array and the tine structures 24themselves. In an alternate embodiment the tine array material isdeposited with conductive particles, such as gold, silver or carbon, tomake the part conductive and allow for direct electrode conductionthrough the structure. Each rigid tine array 26 may have multipleidentical or unique tine structures ranging in quantity from 20-60 tinesper array. The spacing between the tines 24 is such that the tine array26 can be adequately machined or molded. For manufacturability, thetines 24 may be aligned in rows or a circular pattern and theorientation of the individual tines 24 may vary. Alternate embodimentsmay contain tines numbering anywhere between 10 and 100 per array. Inaddition, the use of tines of various heights may be advantageous toreducing “bed of nails” effect when trying to obtain low skin impedancesin certain parts of the body. The differing tine heights may avoid thedisadvantage of districting the applied pressure evenly betweenidentical length tines and thus being unable to pierce the stratumcorneum.

The base of the tine array 26 may be flat, convex, or any geometry suchthat the base conforms to the shape of the skin at the electrodeapplication site. Alternately, the base may be formed in multiplestepped levels 28 as shown in FIG. 2 to allow better displacement orpenetration of the stratum corneum at more pliable areas of the skin.

In another embodiment shown in FIG. 3A, the tines 24 are formed on thetop surface of the array base. In one embodiment the base 30 of thearray 26 is a round disk with a diameter in the range of 0.25″-0.50″,however it may range in size from 0.10″-1.0″. The shape of the base 30of the array 26 may also be created in any size and geometry such thatthe tine array 26 fits within the area of the electrode 14. The base 30of the tine array 26 may be solid or may contain one or more holes orchannels 32. The holes or channels will allow the passage of conductivegel from the surface of the skin to the surface of the electrode.

An alternate embodiment of the arrangement of the tine array shown inFIG. 4A to 4C is a solid annular ring 36 which contains the tines 24 andwhich includes a central opening 38 to permit gel flow and electricalcontact between the conductive medium and the electrode surface (FIG.4A). Yet another alternate embodiment has a small round tine array thatleaves an outer ring of the electrode surface exposed. Alternateembodiments may contain electrode surfaces up to 1.5″ in diameter. Inyet another embodiment, the gel may be contained in a separate cavityduring storage and gets displaced to the skin site during application orduring the prepping action (FIG. 6).

The time structure is preferably created from a plastic such aspolycarbonate (PC), acrylonitrile butadiene styrene (ABS), nylon, etc.,through the process of injection molding. In the preferred embodimentthe tine structure is created from liquid crystal polymer (LCP), such asVectra E130i manufactured by Ticona Engineering Polymers, Florence, Ky.The material may alternatively by any nonconductive plastic which isrigid, such that the tips do not bend upon contact with the skin;however, this material, as applied to the structure, must not bebrittle, in order to prevent breakage of the tips in the skin. Theentire tine array structure may be created through injection moldingusing the same material in a single piece for both the base 30 andindividual tines 24. Alternately, the tine array may be assembled frommultiple molded pieces. The use of nonconductive material ensures thatoffset voltages are not created by contact between metal and skin. Thepreferred manufacturing method is injection molding due to repeatabilityand low cost of mass production and the preferred array shape of a diskis optimal for efficiency of injection molding techniques. However, thetine array 26 may be formed by machining, etching or printing methods.An alternate embodiment may include the impregnation of the moldedmaterial with carbon nanotubes in order to increase the hardness of thetines 24. The carbon nanotubes may also make the electrode surfacepartly conductive, which aids in signal acquisition.

As shown in FIGS. 5A to 5C, each individual tine 24 is generally taperedfrom base to tip and protrudes in a perpendicular direction from thebase. Thus, the tip of each tine 24 penetrates approximately at a 90degree angle to the skin upon pressing of the electrode against thesurface of the skin. Rigid, perpendicular penetration effectivelycreates repeatable micro-conduits in the stratum corneum with the leastforce required. The geometry, including the aspect ratio of the tine, isdetermined to optimize the sharpness of the tip, the effectiveness ofskin penetration and the manufacturability of the device. The sharpnessof the tip of the tine 24 can be quantified as a radius of curvature.The tines 24 in the arrays 26 have a radius of curvature less than0.02″. Additionally, the height of an individual tine may be in therange of 0.010″-0.080″ though the preferred height is in the range of0.020″-0.040″. The preferred geometry of the tine 24 is that of atriangular pyramid with an isosceles triangle shaped base. The base ofthe triangular pyramid may also be an equilateral or scalene triangle.The geometry of the tine 24 may be various other shapes which allow fora taper from base to tip such as a rectangular pyramid, a half cone witha semicircular base or a full cone with a full circle or an ellipticalbase, or the tine 24 can be in the shape of an obelisk where the taperdoes not necessarily begin at the base of the tine. In a preferredembodiment, one face of the pyramid, preferably the face correspondingto the longest side of the triangle may extend at a 90 degree angle fromthe base.

As shown in FIG. 5B, the cross section of such a tine would be aright-angled triangle having one side as vertical, that is,perpendicular to the base.

Impedance measurements at the skin interface were obtained with abiopotential sensor consisting of an array of four (4) electrodes (in anarrangement as shown in FIG. 1B) each including an embodiment of therigid tine device. This embodiment of the tine device consisted of anarray of twenty four (24) pyramidal tines at 0.030″ in height, and witha sharp point having a radius of curvature less than 0.01″. Themeasurements averaged 7 kΩ with less than 2.6 kΩ standard deviationacross subjects.

Referring to FIG. 1B, an implementation of the skin prepping device isshown in a sensor array. Each electrode area 14 contains multiple tinearrays 26 which are arranged over a layer of conductive material. Theprepping structures or tine arrays 26 are arranged on the individualelectrodes 14 such dun a substructure is created with independentprepping areas. When the individual electrodes 14 with the crestedsubstructure of tine arrays 26 are pressed upon, in order to prep theskin, the tine arrays 26 approach the skin at different angles. Theangulations of the individual tine arrays 26 accommodate skinirregularities in certain areas of the bony or in the softer tissueareas.

In an alternate embodiment, shown in FIG. 6, an exemplary gel storagecontainer or chamber 50 is shown coupled to a prepping device 60. Incertain embodiments, the gel storage container may be a burst container.The burst container is designed to open upon the application of force.The gel storage container 50 will hold the conductive gel separate fromthe electrode and prepping mechanism until the sensor is applied to apatient's skin. This will aid in a longer shelf life for the sensorsince any dryout by the conductive gel will be avoided during storage.The gel storage container 50 is shown with a ring prepping mechanism,however, the gel storage container may be used in combination with anyof the skin preparation mechanisms shown. In the illustrated embodimentof FIG. 6, the prepping mechanism includes a base member 62 that iscontiguous with a plurality of generally pyramidal tines 64. Each tine64 may have a concave side that is aligned with a curved sidewall of anaperture or hole 66 formed in the base member 62 of the prepping device60. In some embodiments, the gel storage container is designed such thatapplying pressure on the skin prepping device causes the gel to flowfrom the gel storage device through the aperture into the area betweenthe prepping device and the skin. This serves to precisely place the gelat the site of the micro conduits created by the time arrays.

Turning now to FIG. 7A, an alternate prepping mechanism or device 70 isshown. The prepping device 70 may include a plurality of holes orapertures 72 formed in a base member 74. The base member 74 is shown asrectangular in shape, but other shapes may be used. The base member 74may also include a plurality of tines 76. Each tine 76 is generallypyramidal in shape having a concave side wall. In the preferredembodiment, the concave sidewall is perpendicular to the base of thepyramid as shown in FIG. 7B. This tine construction of a pyramid with aperpendicular concave wall creates a much sharper edge than a pyramidalone, as is evident by the smaller radius of the tip of the preferredconstruction in comparison to an equivalently-sized pyramid without aconcave wall. The concave sidewall of the tine 76 is aligned with asidewall of one of the apertures 72 in the base member 74. Although, theillustrated embodiment of FIG. 7A shows four fines 76 for each aperture72, any number of tines 76 may be provided for each aperture 72.

In FIG. 7B, an enlarged drawing of a generally pyramidal tine 76 isshown. The concave sidewall 78 is shown as extending from the apex ofthe pyramid through the base of the pyramid. This curved sidewall 78 maybe aligned with an aperture formed in the base member 74.

In FIG. 7C, an alternate embodiment of a prepping device or mechanism 70including the generally pyramidal tines 76 is shown. In this embodiment,an exemplary tine pattern is shown. The tines 76 in combination with theapertures 72 is shown in a cross pattern. Any pattern using thecombination of tines 76 and apertures 72 formed in the base member 74may be used to form a prepping device or mechanism. The pattern shownhere is one example of a pattern that is contemplated.

While the foregoing invention has been described with reference to itspreferred embodiments, various alterations and modifications may occurto these skilled in the art. All such alterations and modifications areintended to fall within the scope of the appended claims.

1. A skin preparation device comprising: a base member in the shape of aring; an array of rigid tines contiguous with the base member, each tinehaving a sharp tip adapted to penetrate stratum corneum and to reduceskin impedence and each tine has a height between 0.020 inches to 0.040inches from the base member; and a component configured to deliver aconductive gel below the stratum corneum.
 2. The skin preparation deviceof claim 1, wherein the component configured to deliver the conductivegel comprises a gel storage container coupled to the base member.
 3. Theskin preparation device of claim 2 wherein the gel storage container isa burst container adapted to release the conductive gel when pressedupon.
 4. The skin preparation device of claim 1 wherein the componentconfigured to deliver the conductive gel comprises: a channel extendingthrough the base member, wherein the channel is adapted to allow passageof the gel through the base member.
 5. (canceled)
 6. The skinpreparation device of claim 1 wherein the tines are molded with aplastic resin containing carbon nanotubes.
 7. A skin preparation devicecomprising: a base member; an array of rigid tines contiguous with thebase member, each tine having a sharp tip adapted to penetrate stratumcorneum and to reduce skin impedence and each tine has a height between0.020 inches to 0.040 inches from the base member; a componentconfigured to deliver a conductive gel below the stratum corneum; andwherein the base member is formed of multiple stepped levels each levelcontaining a portion of the array of rigid tines.
 8. The skinpreparation device of claim 7, wherein the component configured todeliver the conductive gel comprises a gel storage container coupled tothe base member.
 9. The skin preparation device of claim 8 wherein thegel storage container is a burst container adapted to release theconductive gel when pressed upon.
 10. The skin preparation device ofclaim 7 wherein the component configured to deliver the conductive gelcomprises: a channel extending through the base member, wherein thechannel is adapted to allow passage of gel through the base member. 11.(canceled)
 12. The skin preparation device of claim 7 wherein the tinesare molded with a plastic resin containing carbon nanotubes.
 13. A skinpreparation device comprising: a base member; and an array of tinescontiguous with the base member, each tine having a pyramidal shapewherein one side of the pyramid is concave.
 14. The skin preparationdevice of claim 13 further comprising: a plurality of aperturesextending through the base member, wherein the concave side of thepyramidal tine is aligned with a sidewall of one of the plurality ofapertures.
 15. The skin preparation device of claim 14 wherein eachaperture has the concave side of one tine aligned with the sidewall ofthe aperture.
 16. The skin preparation device of claim 14 wherein eachaperture has the concave side of two tines aligned with the sidewall ofthe aperture.
 17. The skin preparation device of claim 16 wherein thepyramidal tines are equally spaced around the perimeter of the aperture.18. The skin preparation device of claim 13 further comprising: aseparate gel storage container coupled to the base member.
 19. The skinpreparation device of claim 13 wherein the gel storage container is aburst container adapted to release a gel when pressed upon.
 20. The skinpreparation device of claim 13 further comprising: a channel extendingthrough the base member, wherein the channel is adapted to allow passageof gel through the base of the member.
 21. The skin preparation deviceof claim 13 wherein the tines of the tine array are 0.010 inches to0.080 inches in height from the base member.
 22. The skin preparationdevice of claim 13 wherein the tines are molded with a plastic resincontaining carbon nanotubes.
 23. A sensor system comprising: a flexiblesubstrate; a plurality of electrodes coupled to the flexible substrate;an adhesive substrate adjacent to each of the electrodes and theflexible substrate; and a preparation device comprising: a base memberin the shape of a ring; an array of rigid tines contiguous with the basemember, each tine having a sharp tip adapted to penetrate stratumcorneum and to reduce skin impedence and each tine has a height between0.020 inches to 0.040 inches from the base member; and a componentconfigured to deliver a conductive gel below the stratum corneum. 24.The sensor system of claim 23 wherein each electrode is coupled to aplurality of preparation devices, the preparation devices are arrangedsuch that upon application of pressure to the electrode the preparationdevices angle to adjust to the surface to which the sensor system isapplied.
 25. A sensor system comprising: a flexible substrate; aplurality of electrodes coupled to the flexible substrate; an adhesivesubstrate adjacent to each of the electrodes and the flexible substrate;and a preparation device comprising: a base member; an array of rigidtines contiguous with the base member, each tine having a sharp tipadapted to penetrate stratum corneum and to reduce skin impedence andeach tine has a height between 0.020 inches to 0.040 inches from thebase member; a component configured to deliver a conductive gel belowthe outermost layer of the stratum corneum; and wherein the base memberis formed of multiple stepped levels each level containing a portion ofthe array of rigid tines.
 26. The sensor system of claim 25 wherein eachelectrode is coupled to a plurality of preparation devices, thepreparation devices are arranged such that upon application of pressureto the electrode the preparation devices angle to adjust to the surfaceto which the sensor system is applied.
 27. A sensor system comprising: aflexible substrate; a plurality of electrodes coupled to the flexiblesubstrate; an adhesive substrate adjacent to each of the electrodes andthe flexible substrate; and a preparation device comprising: a basemember; and an array of tines contiguous with the base member, each tinehaving a pyramidal shape wherein one side of the pyramid is concave. 28.The sensor system of claim 27 wherein each electrode is coupled to aplurality of preparation devices, the preparation devices are arrangedsuch that upon application of pressure to the electrode the preparationdevices angle to adjust to the surface to which the sensor system isapplied.